Building Windows Forms Applications - Beginning C# 5.0 Databases - page 152

Figure 9-18. Using CheckBox and RadioButton with UserInfo Windows Forms application
How It Works
Let's take a look at the “Adding a New Form to the Windows Project” task first and understand the code,
button by button and line by line.
First you have an Add button, which adds the country and state to the ListBox and ComboBox. The
ListBox and ComboBox controls have a collection named Items , and this collection can contain a list of
items, which is why you use it here. Next you call up the Add method of the Items collection, and finally
you pass the value entered in the TextBox to the ListBox's or ComboBox's Items collection's Add method,
as shown here:
lstCountry.Items.Add(txtCountry.Text);
Also, once an item is added, for a better user experience, it is advisable to clear the text box so a user
can type a new value with ease.
txtCountry.Clear();
You repeat the same for the ComboBox:
cboState.Items.Add(txtState.Text);
txtState.Clear();
For the Remove Country and Remove State buttons, you follow a similar approach as the Items
collection, but this time instead of Add() you call the Remove() method, and as you know, the
prerequisites for an item removal is that and item has to be selected first either in the ListBox or the
ComboBox. Hence, the code seeks a SelectedItem to be passed to the Remove() method.